Weak Convergence of Hedging Strategies of Contingent Claims

This paper presents results on the convergence for hedging strategies in the setting of incomplete financial markets. We examine the convergence of the so-called locally risk-minimizing strategy. It is proved that such a choice for the trading strategy, when perfect hedging of contingent claims is infeasible, is robust under weak convergence. Several fundamental examples, such as trinomial trees and stochastic volatility models, extracted from the financial modeling literature illustrate this property for both deterministic and random time intervals shrinking to zero.Weak convergence; Incomplete financial markets; Locally risk-minimizing strategy; Hedging strategy; Minimal martingale measure

Opportunity and/or necessity entrepreneurship? The impact of the socio-economic characteristics of entrepreneurs

Few studies have tried to identify the impact of the socio-economic characteristics of entrepreneurs on their opportunity-necessity positioning. Based on a sample of 538 entrepreneurs, we point out that individuals who get involved in an entrepreneurial process, have encountered a situation of necessity and/or opportunity and that the latter can take various forms. We point out the impact of the socio-economic characteristics of entrepreneurs on the alignment of their project with a necessity or opportunity entrepreneurial dynamics. The existence of sub-profiles of entrepreneurs within the necessity-opportunity typology is also highlighted. We point out, for instance, that not all jobseekers are necessity entrepreneurs and that new venture creation based on family pressure may convey both a necessity and opportunity dimension. Finally, our survey reveals a new kind of entrepreneurship: the hobby entrepreneurship.Necessity - Opportunity - motivations

Hugues Faure, 1928–2003: The unique adventure of his life

Hugues Faure was not only one of the greatest pioneers of the study of the Quaternary and a man of outstanding personality, with the highest integrity, an uncommon strength of character, with a lot of kindness and generosity, but also a man who made his dreams, conceived in the inhospitable solitudes of the Sahara, come true. He was very young when he chose his way: barely 10 years old and his passion for geology already filled his life. It was in Africa, a continent he discovered at his earliest years as a field-geologist, and deeply loved, that he nursed and matured many of his most stimulating ideas on Quaternary environmental change. It was in the desert that he built up his exceptional personality and found his truth, which finally allowed him to accomplish his destiny. Hugues Faure was born in Paris, on the 11th March 1928, the son of a jeweller. The comfortable circumstances of the family were darkened by his father's death when Hugues was only 3 years old. As a consequence of this sad event, Hugues used to spend in England most of his school holidays far from his family. Then during World War 2, he lived the exodus on the roads of France, cycling under the bombs, with his dog in his basket. He was 12 years old, and it was the end of his youth. His passion for earth sciences had began before the age of ten, when he started collecting flint and fossils from the chalk of the Paris Basin, and decided to stop playing piano, so as to devote himself to Geology. Hugues graduated in Mathematics from Lycée Jacques-Decour in 1948, and in Sciences from the Faculté des Sciences de Paris Sorbonne in 1949. On the same year he enrolled as a geologist of the “France of Overseas”, then as a hydrogeologist at the French Geological Survey (BRGM) (1949–1963), so as to work in Africa

Nanocalorimetry

International audience1. Definition Calorimetry is the part of thermodynamics which aims to measure any quantity of heat (enthalpy, specific heat, heat release) stored, released or brought into play in any state of matter, in a reaction, or in phase transitions [Lavoisier1780]. More precisely, the terminology of "Nanocalorimetry" may cover different concepts depending on the area of science where it is used. It concerns any calorimetric method in which either the samples to be studied have a size in the range of the nanometer scale or the measured energies involved are of the order of the nanojoule or below

Global Qualitative Behavior of a Class of Nonlinear Biological Systems; Application to the Qualitative Validation of Phytoplankton Growth Models

In this paper we propose a methodology to analyze the global qualitative behavior of a class of nonlinear differential systems with respect to their structure. This class of loop structured systems with monotonous interactions encompasses numerous biological models. We show that, independently of the parameters values or of the analytical formulation of the system, the possible successions with respect to time of some qualitative events that characterize the transients of state variables are strongly related to the signs of the Jacobian matrix (structure of the model). We propose a procedure to derive the transition graph; this graph summarizes the set of possible qualitative features for the state according to the structure of the model. The comparison of the graph with experimental (even noisy) data allows to validate directly this structure. The method is illustrated with a set of models usually used to describe phytoplanctonic growth in the chemostat. The corresponding transition graphis derived and compared with experimental data

Le télétravail des cadres : entre suractivité et apprentissage de nouvelles temporalités

International audienceLe télétravail est souvent considéré comme un moyen d'améliorer l'articulation entre vie professionnelle et vie privée. Toutefois, pourquoi certains salariés, et singulièrement des cadres, en viennent-ils à choisir cette modalité ? S'agit-il d'ailleurs bien d'un choix ou de l'adoption d'une solution « faute de mieux », dans un contexte organisationnel contraignant ? Et dans ce cas, à quels arbitrages temporels procèdent-ils ? Par ailleurs, dès lors qu'ils ont opté pour le télétravail, comment les cadres parviennent-ils à accommoder les contraintes professionnelles et familiales ? Leurs aspirations à une meilleure conciliation sont-elles satisfaites ou rencontrent-ils des difficultés insoupçonnées ? Le présent article apporte des réponses à ces différentes questions, en s'appuyant sur deux études menées auprès de cadres pratiquant différentes formes de télétravail. Il souligne, finalement, que l'absence d'une régulation institutionnelle de l'articulation entre vies privée et professionnelle loin d'assurer une existence plus équilibrée, présente des risques sur l'efficacité collective

Catalogue des ravageurs d'intérêt agricole de Nouvelle-Calédonie

Ce document à double entrée, zoologique et botanique, recense tous les ravageurs d'intérêt agricole (acariens, insectes, mollusques, vertébrés) signalés en Nouvelle-Calédonie (435 espèces), avec leurs plantes-hôtes, la source de l'information, et une documentation photographique importante. (Résumé d'auteur

Correction of megavoltage cone-beam CT images of the pelvic region based on phantom measurements for dose calculation purposes.

Megavoltage cone-beam CT (MVCBCT) is an imaging technology that provides a 3D representation of the patient in treatment position. Because it is a form of x-ray tomography, MVCBCT images give information about the attenuation coefficients of the imaged tissues, and thus could be used for dose calculation. However, the cupping and missing data artifacts seen on MVCBCT images can cause inaccuracies in dose calculations. To eliminate these inaccuracies, a correction method specific to pelvis imaging and based on phantom measurements has been devised. Pelvis-shaped water phantoms of three different sizes were designed and imaged with MVCBCT. Three sets of correction factors were created from the artifacts observed in these MVCBCT images by dividing the measured CT number by the predefined CT number for water. Linear interpolation is performed between the sets of correction factors to take into account the varying size of different patients. To compensate for the missing anatomy due to the limited field of view of the MVCBCT system, the MVCBCT image is complemented with the kilovoltage CT (kVCT) image acquired for treatment planning.When the correction method is applied to an anthropomorphic pelvis phantom, the standard deviation between dose calculations performed with kVCT and MVCBCT images is 0.6%, with 98% of the dose points agreeing within +/- 3%.With uncorrected MVCBCT images this percentage falls to 75%. An example of dose calculation performed with a corrected clinicalMVCBCT image of a prostate cancer patient shows that changes in anatomy of normal tissues result in variation of the dose distribution received by these tissues.This correction method enablesMVCBCT images to be used for the verification of the daily dose distribution for patients treated in the pelvis region